On obtaining of the Alexander Graham Bell a patent for invention of the telephone in 1987, the communication system consistently has gone through several evolutionary stages: from analog lines and manual switches to video telephony and IMS architecture. Each of the stages can be described by specific switching systems, data transmission systems and types of transmitted information. After implementation of such solution, it is possible to create a number of access nodes in the Operators IMS-network during very short time. From point of view of IP-telephone network, there are 10 000 subscribers connected to each of such nodes. As after reconstruction all exchanges are connected to IP-network, all intermediate entities (IISE and OISE) could be dismantled completely. After such modernization, subscribers of ex analog segment get full access to IMS services and functionality.